Hey, I ran into something I haven't done for a long time and can't remember how.
I want to record automation of a VSTi knob. Usually I draw in whatever automation I need but in this case it's more useful to just record the knob movement for various reasons. In Ableton I just touch it while the automation lane is open.
I have the write automation enabled, but nothing seemingly gets recorded if I move the knob while playing or recording.

Hum, sounds like you're doing it right. Might the knob be unautomatable? Can you assign an enevelope to it manually?

Is the auto punch in switch enabled?  If so, automation writing will only occur within its boundaries.
 
Disable the auto punch-in button.  Enable the write automation button on the plugin itself.  Start playback and wiggle the controls.

I forgot to enable write automation on the plug itself, DUH haha. Thanks. I clicked the track one and assumed that was it.

can I suggest you mark this as [solved]?.. thx!